<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>Insert title here</title>
    <script type="text/javascript">

        function test () {
            document.getElementsByTagName("body")[0].innerHTML = '<img alt="beatiful" src="san.gif" width="100%" height="100%">';
        }
        setTimeout("test()", 5000);

    </script>
</head>
<body>

<h1>美女来了！！！</h1>


</body>
</html>